Pipeline leak detection device

ABSTRACT

A DEVICE FOR USE IN DETECTING LEAKS IN A BURIED PIPELINE COMPRISING A PAIR OF CONDUCTORS POSITIONED BENEATH SAID PIPE AND SPACED APART BY AN INSULATION WHICH IS DEGRADABLE BY THE FLUID CONTAINED WITHIN SAID PIPE AND SUBSTAN-   TIALLY IMPERVIOUS TO GROUND WATER OR OTHER LIQUIDS WHICH MAY CONTACT THE INSULATION DURING USE.

Feb 16, 1971 E. o. BUTTS 4, 2 PIPELINE LEAK DETECTION DEVICE Filed Nov.16. 1967 My'Su/HY FAN-T 23 A510 AZAEM I 9 22 ZOCAT/NQ F met A Clean 72vUnited States Patent U.S. (:1. 340-242 4 Claims ABSTRACT OF THEDISCLOSURE A device for use in detecting leaks in a buried pipelinecomprising a pair of conductors positioned beneath said pipe and spacedapart by an insulation which is degradable by the fluid contained withinsaid pipe and substantially impervious to ground water or other liquidswhich may contact the insulation during use.

The present invention relates to apparatus for detecting leaks inpipelines carrying fuel oils, crude oils or other hydro-carbons inliquid or gaseous form.

Numerous attempts have been made in the past to develop apparatus fordetecting leaks in pipelines and many devices have been patented forthis purpose. All of these devices however, have suffered fromlimitations of one sort or another which have prevented the successfuldetection of pipeline leaks.

One prior device for detecting leaks in pipelines is shown in U.S.Patent 3,060,315 to Scherbatskoy. This patent teaches the use of anexploring instrument inside the pipeline to detect the accumulation ofleakage outside the pipe by an n-garnma reaction. The exploringinstrument contains a neutron source together with a gamma detector andis passed internally of the pipe to locate leaks.

It will be appreciated that such a device is of limited usefulness sinceit may only be inserted in pipes of a suflicient diameter to carry theexploring instrument and will only detect leaks where an adequate fluxof gamma rays reaches the detector.

United States Pat. No. 3,025,606 shows another device developed fordetecting pipeline leaks. This device is limited to use between twomanholes in an underground conduit system and would not be suitable fordirect burial with a pipeline. Other devices such as shown in U.S. Pat.No. 3,170,152 have been developed but have not been satisfactory.

The present invention provides a leak detection system with a leakdetector which may be buried directly with the pipeline and which can beused with branched or distributor type systems and will accuratelydetect leaks and pinpoint their location so that appropriate repairs canbe effected. The present invention is particularly suited for buriedpipes which are used in distribution systems for domestic grades of fueloil throughout residential subdivisions.

The basic concept of the invention consists in position ing a pair ofinsulated conductors adjacent the buried pipe, the action of a fluidleaking from the pipe serving to destroy the insulation between theconductors, causing a short circuit and permitting a flow of currentfrom one conductor to the other.

In accordance with one embodiment of the invention, a' first copper wireinsulated with a butyl rubber compound and spirally wrapped with'asecond bare copper wire, is buried together with and immediately beneatha pipeline to be protected, and the action of the fluid leaking from thepipeline serves to degrade or perish the insulation causing a short. Thefirst and second wires are connected to a suitable source of highvoltage, and when 3,564,526 Patented Feb. 16, 1971 the short occurs, acurrent flows between the insulated conductorand the outer wrapping.

This flow of current operates an alarm to indicate the presence of aleak. Preferably the source of high voltage is a high resistance or highleakage reactance type of supply so that the current drawn by a shortcircuit will be limited. The insulated wire with its bare wire wrappingis preferably laid immediately beneath the pipeline and fastened to thepipe by any suitable means, such as an adhesive tape so that any leakagewhich occurs will immediately contact the insulation causing the desiredbreakdown. Once the breakdown has occurred then the location of thebreak is readily pinpointed using known types of equipment, such asconventional telephone cable fault measuring equipment. In accordancewith a further aspect of the invention it is contemplated that the alarmsystem connected to the leak detector of the present invention would bemaintained in acentral location such as at a telephone exchange wherefull fault locating facilities are available. Thus a pipeline leak wouldimmediately be detected and the location of the leak could be determinedwith a minimum of delay.

It is desirable that breakdown in the insulation between the twoconductors should be a permanent low resistance short which would assistin detecting the location of such breakdowns. The fact that a shortlength of electrical cable requires replacement when a leak is repairedis inconsequential compared with the benefit obtained from being able todetect and accurately pinpoint leaks at an early stage beforesubstantial leakage and damage occurs.

In accordance with the present invention a device for detecting'leaks inburied pipelines comprises a pair of conductors positioned beneath saidpipe and spaced apart by an insulation which is degradable by the fluidcontained within said pipe and substantially impervious to ground wateror other liquids which may contact the insulation during use.

In drawings which illustrate the construction and use of devices inaccordance with-the present invention,

FIG. 1 is a schematic view of a portion of a buried pipeline fitted witha detector constructed in accordance with the present invention.

FIG. 2 is a cross section of the pipeline shown in FIG. 1,

FIG. 3 is a perspective view of one form of detection device suitablefor use in accordance with the present invention, and

FIG. 4 is an electrical schematic diagram of the connection andoperation of the detection device of the present invention.

Referring to FIG. 1 there is shown a pipeline 10 beneath which adetector wire constructed in accordance with the invention 11 ispositioned. The device 11 is illustrated in FIG. 1 as fastened to thepipe 10 by suitable fastenings 24 and 25 which may for example bewrappings of an adhesive tape, metal bands or any suitable means. Thewrappings 24 and 25 serve mainly to hold the device 11 in place beneaththe pipe while the pipe is being buried so that any leakage which occurswill immediately alfect the insulation of the device 11. As illustratedin FIG. 1, a pair of terminals 12 and 13 are provided which areconnected to each side of the electric circuit of the device 11 forenergizing the device during operation.

FIG. 2 is a cross section of the pipe 10 of FIG. 1 showing the device 11positioned immediately beneath the pipe 10 in intimate contact therewithso that the smallest leak will reach the device 11 and cause itsoperation as explained hereinafter.

FIG. 3 illustrates the structure of one embodiment of the device 11which consists of a central copper condoctor 14 surrounded with a butylrubber insulation 15.

On the outside of the insulation -a-second copper conductor 16 iswrapped in a spiral.

Preferably the spiral conductor 16 is tensioned at the time that it iswrapped about the conductor 14 and insulation 15, so that thedegradation of the insulation 15 will permit the conductor 16 to workits way into the insulation 15 and thus reduce the spacing between theconductors 14 and 16, thereby accelerating the action of the device 11.

It will be appreciated that the device 11 may take alternative formssuch as for example a pair of parallel conductors which are surroundedby a suitable insulation. In this regard it will be appreciated thatbutyl rubber is only one of a number of suitable insulations which maybe used in accordance with the present invention. Such insulations mayalso comprise plastic and asphaltic compositions, the sole criterionbeing that the insulation is sufliciently degraded to permit a shortcircuit to occur between the two wires and cause a suflicient flow ofcurrent to energize the alarm. With the use of butyl rubber for example,it has been found that fuel oil destroys the insulation very quicklypermitting contact to be made between the wires permitting the passageof an alarm current.

FIG. 4 schematically illustrates the connection of the device 11 bymeans of a double-pole, double-throw switch 17 to the terminals 18 and19 of a high voltage supply and alarm circuit 20, or alternatively to'the' terminals 21 and 22 of fault locating circuitry 23. It will beappreciated that the device 11 may either be connected to the highvoltage supply at all times, or alternatively it may be intermittentlyconnected to the supply 20 for a test period suflicient to determinewhether or not a leak has occurred in the pipeline.

It will be appreciated that numerous changes may be made within thescope and spirit of the present invention, which is defined by theappended claims.

I claim:

1. A device for use in detecting leaks in a buried oil pipelinecomprising a first copper conductor, butyl rubber insulation surroundingsaid first conductor, a tentioned second copper conductor spirallywrapped around said insulation, said first and second conductors beingfor connection to asource of high voltage, whereby destruction of saidbutyl rubber by said oil causes a short circuit between saidfirst andsecond conductors to'indicate a leak from said pipe.

. 2. In a system for detecting leaks in an oil pipeline buried in theground including a source of voltage having a pair of terminals andfault measuring equipment for detecting and locating short circuits, theimprovement comprising in combination a pair of electrical conductorsconnected to said terminals and separated by butyl rubber electricalinsulation degradable by the oil in said pipeline, said conductors beingurged toward each other and thereby compressing said insulationtherebetween, said conductors and said insulation being positionedbeneath said pipeline to expose said insulation to 4 fluid'deaking from'said-pipelineto cause a 'short circuit between said conductors onleakage of oil from said pipeline.

3. A method of locating leaks of oil from a buried pipeline by a leakdetection device ofthe typehaving first and second.copper conductorsseparated by butyl rubber insulation subject to destruction by said oil,comprising:

positioning said leak detection device beneath said pipeline duringconstruction,

connecting said first and second conductors to a source of high voltageof the type having a high resistance or high leakage reactance to causethe current in said conductors to be limited when said insulation isdestroyed by leakage to cause a short circuit between said conductors,

actuating an alarm circuit by said short circuit'current,

disconnecting said leak detection device from said high voltage sourceon actuation of said alarm, and

connecting said first and second short circuited conductors toelectrical fault locating apparatus for determining the location of saidshort circuit thereby to locate said pipeline leak.

4. Apparatus for locating leaks of oil from a buried pipeline comprisinga leak detection device having first and second copper conductorsseparated by butyl rubber insulation subject to destruction by said oilpositioned beneath said pipeline during construction,

a source of high voltage of the type having a high resistance or highleakage reactance, said first and second conductors being connected tosaid source of high voltage to cause a current to flow in said first andsecond conductors when said insulation is destroyed by leakage, thecurrent in said conductors being limited when a short circuit occursbetween said conductors,

- an alarm circuit actuated by said short circuit current,

and electrical fault locating apparatus for determining the'location ofsaid short circuit thereby to locate said pipeline leak.

References Cited uNrrno STATES PATENTS 1,648,197 11/1927 Roodhouse20061.05 2,432,367 12/19 7 .Andresen zoo- 1.04 2,759,175 8/1956 Spalding340-242 3,382,493 5/1968. Loper, 11., et al. 340-242 3,427,414 2/1969.Sheldahl ZOO-61.08

Y FOREIGN PATENTS 1,092,693 11/1960 Germany 17411 707,353 6/1941 Germany340 242 THOMAS B. HABECKER, Primary Examiner D. MYER, Assistant ExaminerUS. Cl. X.R.

